Black line in top panel after mesa update

Hello good people of UM,

I just had a problem appear once I updated the mesa drivers today on UM20.04. I think it's a bug or an issue with the screen on my laptop. A thin black line shows up in my top panel & nowhere else. I would post a screenshot but the thin black line doesn't show up when I take a screenshot. So I took a photo with my phone instead:

Changed the refresh rate - no change (changed to 60 mhz from 120 and back again). Rebooted the system - no change.

Thanks for all your help!

It looks more like hardware failure than anything else.
To be shure, could you boot from the live-cd and see if that makes a difference ?
And if it does, can you post the output of the following command ?
inxi -GC

Do follow what @tkn says above, if you can, but I've got commentary of my own.

I've seen similar things in the past (for example, Ubuntu 11.04 with Unity had a bug with certain Intel integrated graphics chipsets and the window manager decorations used to show up a bit scrambled). I'm fairly sure the problem in that case was related to a buggy Mesa driver in some way or another; for the record, the problem did not appear in Ubuntu 10.04 or 12.04, so whatever the problem was, it was not an issue in a prior release and was fixed by a later release. Well, not surprising; I'm just saying the bug (in my case) was not caused by hardware.

If you move the top panel to another location on the screen (just temporarily), such as the bottom of the screen, does the line linger? And if you then reposition the panel at the top, does the line still linger (or come back)?

From window manager decorations (this was not a compositing window manager either) to "floating" panels, I think Mesa drivers play a bigger role in the desktop's graphics rendering than anybody would like you to believe.

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@tkn I booted into a live environment and the line is now slightly thicker & white instead of black.

Here's the output from the command you gave me when I boot into my system:

  Topology: Quad Core model: Intel Core i7-4702MQ bits: 64 type: MT MCP 
  L2 cache: 6144 KiB 
  Speed: 1202 MHz min/max: 800/3200 MHz Core speeds (MHz): 1: 998 2: 999 
  3: 997 4: 998 5: 998 6: 1002 7: 998 8: 998 
  Device-1: Intel 4th Gen Core Processor Integrated Graphics driver: i915 
  v: kernel 
  Device-2: NVIDIA GM107M [GeForce GTX 850M] driver: nvidia v: 470.82.00 
  Display: x11 server: X.Org 1.20.11 driver: modesetting,nvidia 
  unloaded: fbdev,nouveau,vesa tty: N/A 
  OpenGL: renderer: NVIDIA GeForce GTX 850M/PCIe/SSE2 
  v: 4.6.0 NVIDIA 470.82.00 

@gordon When I move the panel from the top to the bottom, the line still appears at the top. It now appears on the wallpaper instead of the panel. The bug thing sounds logical to me, that was my first guess after it appeared immediately after I updated those drivers.

If you guys need any other info to troubleshoot - let me know!

If the problem was the driver update, you should not have any visual artifacts by booting the (older) live environment. Therefore I really suspect a hardware problem.

Another test: Is the line gone when you switch from the Intel GPU to the Nvidia GPU ? (or is it visible on both?)

Another test: is the line gone when you switch to a lower resolution ?

Another test: Is the line also visible on an external screen ? (if you connect one)

Another test: is the line visible in your UEFI/BIOS setup screen ?

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@tkn You're definitely right!

I called my local computer parts/repair store today to ask them the same question I posted here. They told me to connect my laptop to an external monitor and see if the line appears. I don't have an external monitor - so I hooked it up to my TV. No line/artifacts on the TV = hardware problem (ie the LCD panel), line still present = driver issue/bug. There were no lines or artifacts present on the TV - so I'm taking the laptop in tomorrow to have the panel replaced.

Thanks for all your help @tkn @gordon - you guys really know your stuff!


So... So far, you're rule that "Linux issues" often are actually caused by hardware failures strikes again, eh? I remember last time it was a wireless card; this time it's a display panel.

Well, I guess it's good to know not all problems are caused by software bugs; developers are more competent than they may seem!

Glad to hear you figured out the issue.

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@gordon This is my Linux "rule of thumb" at work again - it looks like hardware issues always trump any software bugs in Linux - particularly with older machines like mine. Actually this will be my go to point for troubleshooting from now on!

What I've noticed is that these finer/intermittent hardware issues show up much better on Linux than windows - windows either hides them or just works around them.

I remember I bought some new ram for my laptop. Same laptop I have now - it's 7 years old & chugging along quite nicely! The windows partition was working fine but the Ubuntu partition was freezing all the time - sometimes after 15 minutes - sometimes after an hour. This was the first time I installed a dual boot setup with Linux & I was like Linux sucks big time! Then I read on a forum that it could be bad ram. I was like - how could it be bad ram - I just bought it a week ago! It suggested to do a memtest to check the ram - and what do you know - the ram was faulty - but it had just started to go bad due to timing/voltage issues. I was like WOW! Linux is awesome! From then on, I nuked my windows partition & just used exclusively Linux from then on!

My experience is that Linux uses the available system hardware to the max where possible (proper drivers available, etc) - that's why it breathes new life into older machines but on the flip side - it also brings to the forefront any bad/flakey hardware much sooner than windows. If I was still running a windows partition, the monitor problem wouldn't appear & then one day the monitor would just stop working. If you're proactive about remedying hardware issues like me - Linux is a Godsend!

After all of these experiences - I'm a Linux convert for life! I will never install a windows partition on my system ever again :slight_smile:

PS Open source devs really catch too much flack for bugs/issues on Linux where the fault also lies with poor hardware/firmware or proprietary drivers - that's just my humble opinion.

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